Help! 1984 300SD, I only have revers now! - PeachParts Mercedes-Benz Forum

Lampbum2 · #1 03-27-2010, 02:15 AM

Hi,
I went into my 1984 300SD trans. to change the B2 piston and it already had the new updated B2 piston in it with the white nylon bushing.

Everything was kept clean and no shop towels were used!!!

The history of the trans. is, it was rebuilt at 144,000 miles. ( first owner had teenage boys ) The trans. now has 302,000 miles on it from me and maintained very well by me, I put all but 11,000 miles on the rebuild.

Symptom #1... about 3 weeks ago I had a flair 2nd to 3rd....Put in a K1 spring and that fixed that.

Symptom #2...about 1 week after the K1 fix.....The car was slipping from a dead stop to a full throttle start......Motor would rev up like a flair/slip until I let up on the throttle... so I was told it was the B2 piston, so I ordered the new B2 piston and all necessary parts.

This trans. already had the new upgraded B2 piston in it and it looked perfect,...But I put the new one in anyway.....went out for a test drive and it did the same thing again.....shifts were all smooth and great UNTIL I stopped at a stop sign and started with the full throttle start and it began to flair/slip again, Only this time I lost all 4 gears...the trans was dead!
I pulled ( coasted ) off the road in to a parking lot.....I sat their for a bit and found I only had reverse.....then after a few more minutes I found it went in to 1st gear....I started back out on the road and tried 2nd gear...it all went dead again.....Finally it went into 1st gear....I drove back to the shop in 1st gear and had to stop just before the drive way and the car would only work in reverse.....So I backed into the drive way on to the lift and their she sits!

So, all I have now is REVERSE ONLY, any ideas?

This trans. has never had anything in the pan ever, no signs of wear ever.....every time I have changed the filter(s) and oil....It has been very clean!

Is it the front pump? Dang I'm stumped!!!

Thank You ahead of time for any help!
Jim

oldsinner111 · #2 03-27-2010, 06:58 AM

Check trans cooler in radiator by looking at ATF color Pink bad, then blow thru lines going in radator and out,(low pressure).If no ptoblems,who rebuilt trans.Most shops unless dealer,or a Mercedes Indie, don't know the tech data. I wish you luck.

layback40 · #3 03-27-2010, 09:06 AM

maybe the pin that the B2 pushes is not right or the band it works to is bad?

vstech · #4 03-27-2010, 11:41 AM

inspect the area where the piston sleeve sits. if it's badly scored/worn, your case could be shot from the original b2 piston metal sleeve, wearing the casing out letting pressure leak... Whunter condemned mine for this issue... he also said if there is even the slightest fluid leaking out of the B2 piston cover, the piston will not work, so thoroughly inspect the cover for leakage.

Lampbum2 · #5 03-28-2010, 02:46 AM

Update on my reverse only trans....No forward gears.

The trans. that was in my car ended up having a broken B2 band, I ended up taking the new K1 spring and new B2 piston out of this broken trans. and putting them in my used back up trans.

The back up trans. runs great so far....much smoother..... In fact it is very smooth, so much more than the one I just removed.....The trans. I just took out had a vibration in it, I always thought it ( the vibration ) was the drive-line.

I was thinking of replacing the broken b2 band, but I don't want to risk having that vibration back so I am going to junk it.

Time to find another trans. or just buy a rebuild.